How to cleanly reboot core OS when "Failed to talk to init daemon" is seen?

Question

How do I cleanly reboot my coreOS after the following issue shows up?

core@node2 ~ $ sudo reboot
Failed to talk to init daemon
core@node2 ~ $ sudo shutdown -r now
Failed to talk to init daemon.
core@node2 ~ $ sudo systemctl reboot
Failed to get D-Bus connection: Operation not permitted
core@contiv-node2 ~ $ shutdown
Must be root.
core@node2 ~ $ sudo shutdown
Unable to perform operation without bus connection.
core@node2 ~ $ cat /etc/lsb-release 
DISTRIB_ID=CoreOS
DISTRIB_RELEASE=991.2.0
DISTRIB_CODENAME="Coeur Rouge"
DISTRIB_DESCRIPTION="CoreOS 991.2.0 (Coeur Rouge)"

Answer 1

sudo reboot -f

-f, --force Force immediate halt, power-off, reboot. Do not contact the init system.

Answer 2

kill -15 1

That should wake up the init daemon and then you should be able to reboot as normal. (i.e. sudo kill -15 1; sudo reboot)

If possible, this is a better solution than reboot -f as you will be able to perform a clean reboot.